Conventional golf balls are of two general types, solid one-piece balls and multi-piece balls. Solid one piece balls consist of a polymeric sphere having a plurality of dimples molded on its outer surface to aid the flight characteristic of the ball. Multi-piece balls consist of either three piece, thread wound balls or two piece balls having a preformed core covered with a separate and distinct cover.
Over sixty years ago, a natural resin, balata, came into widespread usage as a golf ball cover material for multi-piece balls. The recognized advantages of using balata are that it gives the ball a good "feel" when the ball is struck and that "good" golfers are more easily able to control the flight of the ball to their satisfaction. Significant, recognized disadvantages are that a balata cover "cuts" easily, particularly when the ball is miss-hit and that the balata cover reduces the initial velocity or coefficient of restitution when used with a given center. Nowadays, balata covered balls--almost exclusively three-piece balls--have limited market appeal and are generally used only by pro or expert golfers who are primarily interested in controlling the ball.
During the past twenty years or so, synthetic polymeric materials, and mixtures such materials of, have come into widespread use for multi-piece golf ball covers. Such polymeric ball covers are relatively cut-proof when compared to balata covered balls due to the superior toughness of the polymeric materials vis-a-vis the relatively weaker balata. Additionally, they enhance the performance of the balls, whatever the ball's center may be. Largely because of their durability, polymeric covered balls have gained popularity with "average" golfers, and their sales greatly exceed those of balata covered balls. Nevertheless, many existing polymeric covered balls have had difficulty giving the same "feel" and being as "controllable" as balata covered balls. While softer ionomers and the like have been used to enhance the feel of the polymeric covers, on impact, however, they still do not closely approach the feel and distortion of balata covered thread wound golf balls. Achieving this desired "feel" and controllability--while maintaining desired distance characteristics--has long been and remains an important objective of manufacturers of polymeric covered balls.
Another important factor in the marketing of golf balls is the long-held belief that balls which can be driven farther, in terms of carry and roll, are better. Having the longest ball--compatible with the U.S.G.A. requirements--has been and also remains another, longstanding objective of golf ball manufacturers. In this respect, prior balata and polymeric covered balls, and certainly those intended for U.S.G.A. regulation play, have shared one thing in common. They have all relied on their preformed cores as the primary vehicle for transferring energy from the golf club to the ball when the ball is struck by the club. For years, the principle thrust of golf ball research and development has been directed to making improved preformed cores for enhancing distance performance. In other words, conventional wisdom among golf ball manufacturers has been that enhanced distance performance is primarily achievable through the use of better energy transferring cores.
This is not to say that some did not recognize that the cover composition could contribute to the ball's distance performance. U.S. Pat. No. 3,819,768, which issued in the name of Robert P. Molitor (one of the named inventors herein) and which disclosed the use of mixed "SURLYN" resins as a ball cover material, recognized that the use of a mixed "SURLYN" cover could and did increase the distance the ball could be driven. Nevertheless, the cores of the balls manufactured under U.S. Pat. No. 3,819,789 still were preformed and were believed to be a significant contributor to energy transfer. The coefficient of restitution of these cores was approximately 0.750 and the final ball was approximately 0.780.
The approach of utilizing preformed cores as the principal "mechanism" for transferring energy has recognized disadvantages. The cost of manufacturing such preformed cores is a relatively large part of the cost of manufacturing the golf balls. Because of the relative complex technology and operations involved, the use of such preformed cores have also imposed added quality assurance problems and costs.
In summary, those working in the golf ball art have long sought to develop a golf ball that: has the "feel" and controllability of a balata covered three-piece ball; has a high initial velocity or initial coefficient of restitution, has a good "cut resistant" and durable cover; may be driven long distances in regulation play, hopefully by "average" golfers; and, importantly, may be uniformly and inexpensively manufactured by mass production techniques. As noted, to a large extent, the industry has sought to achieve this long recognized and desired objective by using a polymer or balata cover over a preformed core and by enhancing the ball's preformed core's capacity for transferring energy when the ball is struck by a golf club.